gamo dynamax .177

i,ve got a BSA/gamo dynamax .177,bought new 11 months ago...from the get-go this thing has been a problem child,and yet i don't want to give up on it...yet...at first it sprayed pellets in a 12 inch group at 35 yards.it took a while,but i found that was caused by the magazine being made poorly...the exit port of the mag's body wasn't centered with the rotary pellet holder,thus upon loading the pellet into the barrel using the bolt, the pellet nicked the mag's body and damaged it enough to never allow for accuracy...i fixad that by drilling a larger exit port in the mag body... the next problem i am dealing with on this gun is it was shooting jsb 10.34 at over 1050 fps. [is that too fast for such a heavy pellet}? so i did remove the end cap and turned the power down,all the while documenting with a pro chrony the fps/pellet brands/and weights...i,ve got the power down but i still cannot get good groupings even at 10 meters.talk about frustrated LOL...is it possible the barrel has issues...i've also got three dynamaxes in .22 and can say those shoot better than i thought possible.dime sized holes at 35 yards all day long...any suggestions or input.maybe the .177 just isn't as accurate as the .22..i don't know...what are your thoughts,ideas,insights...help...

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